Conventional cable window regulators typically include either a single rail or a pair of rails bolted to a carrier panel mounted within a doorframe. A lift plate is slidably attached to each rail, which in turn holds a window glass. A cable is attached to the top and bottom of each lift plate, and routed around pulleys located around the two ends of the rail. The cable is wound around a cable drum, which is rotated by either a power motor or a hand crank. By engaging the motor, the lift plates can be raised or lowered along the rails between an open and a closed position (i.e., the distance required to move the window between its fully open and closed positions).
Conventional cable window lift systems tend to be vehicle specific. As the window glass moves with the lift plate, and as window glass in automobiles is typically curved, each rail must have a curvature corresponding to the glass and this will vary from vehicle to vehicle and from window to window within a given vehicle. Furthermore, the overall length of the rails is also a concern as the vertical height available within a doorframe is limited in space. A conventional cable window lift system requires an overall height of approximately that of the range of travel required for the lift plates, plus the space required to mount the top and bottom pulleys. The range of travel of the lift plates provided by the window regulator is typically limited to the distance between the pulleys. Any attempt at further travel will result in the lift plate striking either the top or bottom pulley.
US patent application 2004/0163310 to Kirejczyk teaches a rail-less window regulator. A cable window regulator is provided which comprises a first pulley rotatably mounted to a first pulley bracket and a second pulley rotatably mounted to a second pulley bracket. The regulator further comprises a lift plate securable to a window glass, a cable affixed at opposite ends thereof to the lift plate and running over the first and second pulleys. A window regulator drive assembly is operably connected to the cable for causing movement of the cable and in turn moving lift plate relative to the first and second pulleys. The first pulley bracket, second pulley bracket and window regulator drive assembly are mountable to a structure housing, and no rails are used.
By eliminating the need for rails, this cable window regulator simplifies door assembly. In addition, the range of travel of the lift plates spans a distance greater than the distance between the first and second pulleys. However, the rail-less window regulator is not without its own drawbacks. By placing the pulley axes parallel to and spaced apart from the closure pane, the overall thickness of the carrier panel is increased in a doorframe where space is at a premium. In addition, pulley brackets are required, increasing the parts and assembly costs of the window regulator.